Rule: no-non-null-assertion

Disallows non-null assertions using the ! postfix operator.

Rationale

Using non-null assertion cancels the benefits of the strict null checking mode.

Instead of assuming objects exist:

function foo(instance: MyClass | undefined) {
    instance!.doWork();
}

Either inform the strict type system that the object must exist:

function foo(instance: MyClass) {
    instance.doWork();
}

Or verify that the instance exists, which will inform the type checker:

function foo(instance: MyClass | undefined) {
    if (instance !== undefined) {
        instance.doWork();
    }
}

Notes:

Config

Not configurable.

Config examples

"no-non-null-assertion": true

Schema

null